The invention concerns a three-dimensional structure which comprises a planar base and convex curvatures such as cups, bridges or the like which protrude from the planar base in a perpendicular direction.
The expression "three-dimensional structure" denotes a structure which may be, for example, similar to an egg carton in design.
A three-dimensional structural component is known from the German patent document A 3,792,633 which is made by deep-drawing of at least one layer of a knit and a fiber mat which has been impregnated with synthetic resin. Such three-dimensional structural components, termed therein as "structural honeycombs", are especially well suited as core materials for making planar sandwich bodies.
As a rule such structural components may be used as spacers, being lightweight and comparatively stable and mechanically strong.
This known structural component is manufactured by placing a fiber mat consisting of a web or of individual staple fibers arrayed in planar manner on a length of knit material, the fiber mat possibly being covered by yet another length of knit material and, following impregnation with a synthetic resin or a corresponding solution or emulsion, the combined lengths are then subjected to deep-drawing and simultaneous heating.
The known structural component becomes rigid only after the synthetic resin has cured. Using one or more layers of knit material and incorporating synthetic resins makes the product fairly expensive.
During the deep-drawing of the lengths of knits, the threads of these knits usually retain their initial length but may be shifted relative to each other. According to German patent A 3,792,633, the known structural components may contain in excess of 50% by weight synthetic resins, for instance phenol-formaldehyde-resol resins, whereas the knits only amount to less than 25% by weight of the product. Accordingly such a product entails ecological problems both during manufacture and during its later destruction.